The present invention relates to a cam drive for an internal combustion engine in a manually guided implement, especially for a valve-controlled, mixture-lubricated internal combustion engine.
DE 198 48 890 A1 discloses a mixture-lubricated, valve-controlled internal combustion engine according to which the mixture that is supplied to the combustion chamber is supplied via an intake channel and an intake valve. To ensure lubrication of the valve drive and the crank assembly, the valve housing is connected via a connection bore with the mixture-supplying channel, and the crankcase is connected to the valve housing via a channel. During the pulsation in the intake cycle there also results a mixture exchange, and hence a lubrication in the chambers that are connected only via a flow path.
Valve-controlled two-stroke or four-stroke engines run at high speeds, so that the surfaces of the control cams, as well as the cam drive itself, are subjected to high stresses. This can lead to premature wear, especially when there is a lack of lubricating oil.
It is therefore an object of the present invention to improve a cam drive of a valve-controlled internal combustion engine in such a way that in particular during a mixture lubrication an adequate supply of lubricating oil to the moving parts is ensured.